Espressif ESP32-S2 User Manual

Chapter 4. API Guides
Buffer Type Alloc Type Default Configurable Description
Static RX Buffer
(Hardware RX
Buffer)
Static 10 * 1600 Bytes Yes This is a kind of
DMA memory.
It is initialized in
esp_wifi_init()
and freed in
esp_wifi_deinit().
The ‘Static Rx
Buffer’forms the
hardware receiving
list. Upon receiving
a frame over the
air, hardware writes
the frame into the
buffer and raises
an interrupt to the
CPU. Then, the
Wi-Fi driver reads
the content from the
buffer and returns
the buffer back to
the list.
If the application
want to reduce the
the memory stati-
cally allocated by
Wi-Fi, they can re-
duce this value from
10 to 6 to save 6400
Bytes memory. It’
s not recommended
to reduce the con-
figuration to a value
less than 6 unless
the AMPDU fea-
ture is disabled.
Dynamic RX Buffer Dynamic 32 Yes The buffer length
is variable and it
depends on the
received frames’
length. When
the Wi-Fi driver
receives a frame
from the ‘Hard-
ware Rx Buffer’,
the ‘Dynamic Rx
Buffer’needs to be
allocated from the
heap. The number
of the Dynamic Rx
Buffer, configured
in the menuconfig,
is used to limit
the total un-freed
Dynamic Rx Buffer
number.
Dynamic TX Buffer Dynamic 32 Yes This is a kind of
DMA memory. It
is allocated to the
heap. When the
upper- layer (LwIP)
sends packets to
the Wi-Fi driver,
it firstly allocates
a ‘Dynamic TX
Buffer’and makes
a copy of the
upper-layer buffer.
The Dynamic and
Static TX Buffers
are mutually exclu-
sive.
Static TX Buffer Static 16 * 1600Bytes Yes This is a kind of
DMA memory.
It is initialized in
esp_wifi_init()
and freed in
esp_wifi_deinit().
When the upper-
layer (LwIP) sends
packets to the Wi-
Fi driver, it firstly
allocates a ‘Static
TX Buffer’and
makes a copy of the
upper-layer buffer.
The Dynamic and
Static TX Buffer are
mutually exclusive.
Since the TX buffer
must be DMA
buffer, so when
PSRAM is enabled,
the TX buffer must
be static.
Management Short
Buffer
Dynamic 8 NO Wi-Fi driver’s in-
ternal buffer.
Management Long
Buffer
Dynamic 32 NO Wi-Fi driver’s in-
ternal buffer.
Management Long
Long Buffer
Dynamic 32 NO Wi-Fi driver’s in-
ternal buffer.
Espressif Systems 1553
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Release v4.4

Espressif ESP32-S2 Specifications

General

Brand	Espressif
Model	ESP32-S2
Category	Single board computers
Language	English